Drafting instrument



Oct. 13, 1959 J. A. BURKE, JR

DRAFTING INSTRUMENT Filed Jan. 31. 1957 INVENTOR JERRY A. BURKE Jr.

MYM

Aawf/ A. ATTORNEY;

be located.

2,9@8,8l Patented flct. 13, 1959 2,908,081 DRAFTING LNSTRUMENT Jerry A. Burke, Jr kichmond, Va., assignor to Experiment Incorporated, Richmond, Va., a corporation of Virginia Application January 31, 1957, Serial No. 637,466

3 Claims. (Cl. 33 107) The present invention relates generally to the art" of geometric drafting instruments and has specific reference to a scaledrule and a straight edge for guiding scribing instruments such as pens, pencils and the like.

In the use of typical ruled scales for laying out distances in drafting practices it has been necessary to mark points as they are visually projected in extension from scaled reference points on a ruler. Accurate visual projection of such reference projection points is diflicult when dealing with fine tolerances, and such difliculty is increased in the typical ruler construction by the shadowing or shading by the rule body of those areas adjacent the body of the rule where the reference points are to It is therefore a general object of the present invention to provide a unique and greatly improved drafting instrument which provides useful advantages over prior structures of the same general utility.

Another object'of this invention resides in the provision of a new and improved drafting instrument which takes the form of a combination ruled scale and guiding straight edge for scribing implements.

A still further object of this invention lies in the provision of a drafting instrument in the form of a sealed rule wherein the sealed division marks are light projected onto the drafting surface permitting the fast and accurate superimposed scribing of the projected marks directly'on the drafting surface.

Still another object of this invention is the provision of a new and improved drafting instrument of the type hereinbefore described wherein the light projection of the scale division marks additionally serves to illuminate the normally shadowed areas on the drafting surface adjacent the body of the ruler.

A further object and advantage of this invention is the provision of a drafting instrument of the type described which is of a simple, non-complex and relatively inexpensive design and construction.

Still other objects and advantages of this invention will become more readily apparent to those skilled in the art when the following description is read in the light of the accompanying drawings.

In the accompanying drawings:

Fig. 1 is a top plan view of the preferred embodiment of the rule constituting the present invention with fragmentary portions broken away for clearer illustration.

Fig. 2 is a vertical section taken on line 22, Fig. 1.

Fig. 3 is a side elevational view from the vertical plane indicated by line 3-3, Fig. 2.

Fig. 4 is a sectional elevation similar to Fig. 2 of a modified embodiment of this invention. 7

The nature of the present invention may be described in general terms as relating to a drafting instrument including in combination a ruled scale and a straight edge which consists of an elongated fiat body portion, an upstanding handgrip extending longitudinally and substantially centrally of the body portion, at least one longitudinal edge being formed of a light transmitting material and having a central projection extending transversely of the body portion to a point adjacent the longitudinal center thereof, the opposed longitudinal edge of the body portion supporting in an upwardly and outwardly inclined position a transparent panel carrying scale indicia, thereon, a sheet of light transmitting material carried centrally within the body portion throughout the length thereof and extending laterally from a point adjacent the innermost face of the transparent panel to a point adjacent the longitudinal center of the body, and a light source within the handgrip portion in light conducting communication with the innermost edges of the projection of the first named edge forming member and the light conducting sheet extending outwardly to the transparent panel.

As is best illustrated in Figs. 1 and 2 of the drawings, the drafting instrument, generally designated at 10 constituting the present invention, consists of an elongated flat rectangular body portion 12 having an upstanding handgrip member 14 extending longitudinally of the upper face thereof. One vertical longitudinal edge of the body portion or member 12 is horizontally keyed as at 16 substantially centrally of the edge throughout the length thereof and receives a complementary tongue or projection 18 therein which carries a pen or pencil guiding formation 20 thereonin substantially integral lateral projection or extension of the body portion 12.

The second longitudinal edge of the body portion 12 is undercut in a vertical plane and is keyed horizontally inwardly of the body portion throughout its length centrally of its vertiealdepth as at 22 providing an upper lip 24 and a lower lip 26. The upper and lower lip portions 24 and 26 are grooved as at 28 in aligned opposition to each other and said opposed grooves receive and retain in upwardly and outwardly inclined disposition a transparent panel 3%). As is best seen in Fig. 3 of the drawings, the transparent panel 30 carries thereon ruledscale indicia 32 consisting of reference marks indicating linear measurement in typical ruler fashion except that the reference mark indicia appear as a mirror image of the actual scale designations when viewed in side elevation looking in the direction of the body portion of the instrument. Simplified application of such mirror image designations could be easily accomplished by applying the indicia in right reading fashion on the inner face of the transparent panel.

Associated with the horizontal key 22 is a sheet 34 of light transmitting material which completely fills the key and which terminates adjacent the longitudinal centerline of the handgrip portion 14 of the instrument. That longitudinal edge of the sheet 34 adjacent the inner face of the transparent panel 30 is undercut so as to extend inspaced parallel relationship with the inner face of the panel.

Located longitudinally within the handle portion 14 is an elongated light source 36 such as a phosphorescent tube of the like which is energized from an external source through lead in wires 38 connecting in one end of the handle member. The handle member is provided with a longitudinal passage 40 therethrough to accommodate the necessary wiring 42 for completing the circuit through the length of the bulb or light tube 36.

The handle portion 14 directly beneath the light tube 36 is provided with a vertical passage 44 throughout the length of the bulb or tube which communicates at its lower end with the innermost end of the key 22, and the sheet 34 of light transmitting plastic material is provided with an upturned innermost end 46 which places the normal longitudinal inner edge 48 of the sheet horizontally wiihin the passage 44 directly beneath the light tube or bu b 36.

in. construction of the drafting instrument above described it is contemplated that the light transmitting members l8 and 34- would be formed from any suitable transparent or translucent light-bending plastics such as; the

polystyrenes and the poly acrylic and polymethacryli'c esters for example, Lucite brand acrylics.

In the illustrative embodiment of he present invention shown in Figs. 1 and 2 of the drawings the projection or tongue piece 18 of the straight edge guide member 20 terminates short of the light tube 36 and has no light conducting communication therewith. 7 Accordingly, in this embodimentlight (daylight or artificial) will be abl y't e i na rfla upp rfa e of n ids piece a wnby a ows 50am be i e l n he guiding edge, as at 52, to illuminate the adjacent drafting u e-M However, it is fully contemplated as evidenced by the hereinbefore general statementand certain of the hereinafter appended claims, that the tongue or projection piece 18 may be formed integrally with the sheet member 34 in normalprojection thereoflaterally of the body portion of the instrument to provide forthe application of light from the light source 36 to the inner end of the tongue or projection piece 18 which W ll onduct or transmit the light heret eu tqb t d as. a 2 i a manner typical to the characteristics of the light conducting material l It is additionally'pointed out that the panel member 30 forming the ruled scale longitudinally of one edge of the body portion rnaybeof a transparent characteristic, as described, having opaque indicia thereon for the purpose of, light projecting the indicia onto the adjacent draftingsurface in a manner to be hereinafter described. However it is additionally contemplated that the scale panel 3i), may be opaque having transparent ruled scale indicia thereon to permit the light projection of the indicia ontoithe adjacent drafting surface. r

Of "the two above possib mbodiments of the ruled scale structure; the described transparent panel is preferred over the opaque panel since the indicia would be projectedin negative onto the adjacent drafting surfacelmaleing it more distinctiand legible and at the same time gpermittingl a greater emission. of light from the conducting sheet 3 4 through thepanel for illumination of the adjacent drafting surface to eliminate shadows and shading caused by the bodyportion of the draft ing instrument.

In Fig.4 0f the drawings there isillustrat eda modified embodiment in which the instrument consists solely of a light projected ruled: scale without provision of a straight edge construction. In this modifiecl'embodinient an elongated rectangular honsing Sfl is provided along the length ofone side with two .liori zontah vertically spaced, co-extensive flangesf56'and 58 which define an opening60 lo'ngitudinally of. that side w'all of-the housing. In this construction the lower 'fiange 56 terminates inwardly of the hoiising'at a spaced distance from the outer extremity of the lilpper flange '58 the extreme ends of the flanges are providedin directopposition with grooves 62 for supporting an angularly inclined position the hereinbefore described transparent (or opaque) panel 30 on which the scaled in'di'cia' are carried.

Within]the hous ng ssmemhg'at r light tube 64jis slupfpbii d;10hgitudinally 'andis provided with a battery v source '66 operably connected, theretofor energizing the light, .A flatYsheetQof transparent ,or translucent light transmitting material 66 is positioned'between the spaced flanges 56 and, 58 'to extendfro'rn the opening 60 in the housing 'walfoutwardlyto terminate in an angular edge 68 in elos'elfspa'ced parallel adjacency to the'inner face lt'is fullyc'ontemplated.that the battery source of :electric alenergy in the embodiment disclosed in Fig. 4 may bodiment illustrated in Figs; 1' and 2 of the drawings just 4 as the earlier described embodiment could be modified for the inclusion of a battery source of electrical energy.

In the operation of the several illustrative embodiments of the present invention hereinbefore described light applied from the internal light source 36 (and 64) to the light transmitting or conducting member 34 (and 66) respectively will be conducted through these members in a manner common to the characteristics of the material to be emitted from the outermost edges of the material directly adjacent the inner faces of the panel members 30. Light emitted from these members will" be projected through the panel members illuminating, in the case 'of a transparent panel, the normally shaded-areas on the drafting surface adjacent the body portion of the instrument and serving to project'the ruled indicia on the panel onto the drafting surface as shown at 70 in Fig. 1 of the drawings. By applying the ruled indicia to the inner face of the panel, or as mirror images topthe outer face of the panel,'the proj e'cted indicia would appear'in right reading character on the drafting surface facilitating the quick and accurate laying out'offreference points directly on the drafting surface in superimposed manner upon the than the groove 28 so that the panel 30 and its indicia SZ inaybe slid longitudinally within the groove whereby j zferoion the sealernay "be placed at various positions on the drawing area. To facilitate movement of the-scale panel 30'within the groove 23a athurnbpiece may beprovided on the panel asshown at 31 in Fig. 1 of the drawing. It isv also evidentthat anew and improved structure has"been'providedwhich attains and satisfies all of-those objects and advantagesheretofore setfo'rth.

1' claim:; 7 v

1 Aldi'af-t'ing'ins'tiument including an elongated body portion having a base adapted to lie on a drafting surface and at least one longitudinal edge, an indicia-carrying 'rnemb'e'falong said onelongitudinal edge of the-drafting instrument, a source of light, means 'for"applying light "from fthe source 'of light to the'indicia-car'r ying member from the body portion side thereofto project an'ima'ge of the "indicia carried by the indicia-carrying member adjacent said o e edge of the body portion onto' a drafting surface upon'which the base or the instrument lies, said meansfor applying light from said sourcejcoinprising a light-transmitting plastic material positioned between said .along 'said' one longitudinal fledge, said indicia-carrying be modified'to provide fo r external connection to a wall outletor 'the like as. in themanner disclosed in the emmember being inclined upwardly; and outwardly of the base portion of the body oftheQ drafting instrument, a source of light, means for applying light from said source 9] h dicia carrying member from the body portion of'ttofproject an j imagefoffthe indicia on the indlcia-car yi'ngImember, onto. a drafting"surface positioned adj'a'centfsaid one longitudinal edge 'ofithe'body portion,"said means for applying light from said source comprising a light-transmitting' plastic materialjpositioned between 's'aid'indicia carryingfmember and said source of light. 7

3. A drafting-instrument including'afi felongatedbody portion having a light transparent ruled scale 'along'one edge "thereof, opaque ruled. indicia .on' said transparent scale, said scale being inclined upwardly and outwardly .of the bodypoflibn, said scale indicia being applied itothe 1y of said body portion, and means for applying fight t0 the scale from the body portion side thereof whereby the mirror image indicia on the scale will be projected onto an adjacent surface in right reading form.

References Cited in the file of this patent UNITED STATES PATENTS Klein et a1 Apr. 7, 1942 6 Ruth June 12, 1945 Prideaux July 24, 1951 Levy May 26, 1953 Graham Feb. 8, 1955 Leone Apr. 27, 1957 FOREIGN PATENTS Switzerland Apr; 16, 1949 

